Display device with touch detection, drive circuit, driving method, and electronic unit

ABSTRACT

A display device includes: a plurality of drive electrodes; a plurality of detection electrodes intersecting the plurality of drive electrodes; and a scan driving unit performing a first scan drive and a second scan drive. The first scan drive allows a display drive signal for driving the display elements to be applied to each of the plurality of common drive electrodes, and the second scan drive allows a touch detection drive signal for detecting an external proximity object to be applied to each of the plurality of common drive electrodes.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority PatentApplication JP 2010-104051 filed in the Japan Patent Office on Apr. 28,2010, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present application relates to a display device with touch detectionof an electrostatic capacitance type, a drive circuit and a drivingmethod used for the device, and an electronic unit having such a displaydevice with a touch detection.

In recent years, attention is paid to a display device to which acontact detecting device called a touch panel is attached or with whicha touch panel is integrated. The user enters information using variousbutton images or the like displayed in the display device instead ofnormal mechanical buttons. Since such a display device having the touchpanel does not need input devices such as a keyboard, a mouse, and akeypad, the display device is being increasingly used in not only acomputer but also a portable information terminal such as a cellularphone.

One of the touch detecting methods is a capacitive touch detectingmethod. For example, in Japanese Unexamined Patent ApplicationPublication No. 2009-244958, a display device is proposed, in which acommon electrode for display that is originally provided for the displaydevice is also used as one of a pair of electrodes for a touch sensor,and the other electrode (touch detection electrode) is disposed so as tointersect the common electrode. An electrostatic capacitance is formedbetween the pair of electrodes for a touch sensor, and changes accordingto an external proximity object. In the display device, a displayoperation is performed by sequentially applying a drive signal to thecommon electrode and performing a line-sequential scan, and a touchdetecting operation is performed by analyzing a touch detection signalwhich appears in the touch detection electrode in accordance with thedrive signal.

SUMMARY

Since not only a touch component based on the drive signal for the touchdetecting operation but also a touch component based on the drive signalfor the display operation (that is, display noise) are included in thetouch detection signal, an erroneous operation may be caused.

It is desirable to provide a display device with touch detection, adrive circuit, a driving method, and an electronic unit in which theinfluence of the display operation on the touch detecting operation isminimized.

A display device with touch detection according to a first embodimentincludes: display elements; a plurality of common drive electrodesarranged in parallel to extend in one direction; a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unitperforming a first scan drive and a second scan drive, the first scandrive allowing a display drive signal for driving the display elementsto be time-divisionally applied to each of the plurality of common driveelectrodes in succession, the second scan drive allowing a touchdetection drive signal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession; and a detection circuit detecting the externalproximity object based on a touch detection signal which is outputtedfrom the detection electrode in response to application of the touchdetection drive signal. When a common drive electrode selected to bedriven in the first scan drive is coincident with a common driveelectrode selected to be driven in the second scan drive, the scandriving unit applies either the display drive signal or the touchdetection drive signal to the coincident common drive electrode, andwhen a common drive electrode selected to be driven in the first scandrive is different from a common drive electrode selected to be drivenin the second scan drive, the scan driving unit drives the respectivecommon drive electrodes so that waveform of the touch detection drivesignal transits at a timing within a period accompanied by no waveformtransition of the display drive signal.

A display device with touch detection according to a second embodimentincludes: display elements; a plurality of common drive electrodesarranged in parallel to extend in one direction; a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unitperforming a first scan drive and a second scan drive, the first scandrive allowing a display drive signal for driving the display elementsto be time-divisionally applied to each of the plurality of common driveelectrodes in succession, the second scan drive allowing a touchdetection drive signal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession; and a detection circuit detecting the externalproximity object based on a touch detection signal which is outputtedfrom the detection electrode in response to application of the touchdetection drive signal. The scan driving unit drives the common driveelectrodes so that a common drive electrode selected to be driven in thefirst scan drive is not coincident with a common drive electrodeselected to be driven in the second scan drive, and the scan drivingunit drives the respective common drive electrodes so that waveform ofthe touch detection drive signal transits at a timing within a periodaccompanied by no waveform transition of the display drive signal.

A display device with touch detection according to a third embodimentincludes: display elements; a plurality of common drive electrodesarranged in parallel to extend in one direction; a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unittime-divisionally applying a drive signal including a DC waveform and apulse waveform to the plurality of common drive electrodes insuccession, the DC waveform corresponding to a display period which isallocated for performing display by the display element, the pulsewaveform corresponding to a touch detection period which is allocatedfor detecting an external proximity object, and the display period beingseparated from the display period; and a detection circuit detecting theexternal proximity object based on a touch detection signal which isoutputted from the detection electrode in response to application of thedrive signal.

A display device with touch detection according to a fourth embodimentincludes: a display unit displaying an image, and including displayelements, a common electrode connected to the display elements, and acommon signal driving unit applying a common signal to the commonelectrode; and a touch detecting unit detecting an external proximityobject, the touch detecting unit including: a plurality of common driveelectrodes arranged in parallel to extend in one direction; a pluralityof detection electrodes arranged in parallel to extend in a directionwhich intersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unitperforming a scan drive of allowing a touch detection drive signal fordetecting the external proximity object to be time-divisionally appliedto each of the plurality of common drive electrodes in succession; and adetection circuit detecting the external proximity object based on atouch detection signal which is outputted from the detection electrodein response to application of the touch detection drive signal. Thecommon signal driving unit and the scan driving unit drive the commonsignal and the touch detection drive signal so that waveform of thetouch detection drive signal transits at a timing within a periodaccompanied by no waveform transition of the common signal.

A display device according to yet another embodiment includes: aplurality of drive electrodes; a plurality of detection electrodesintersecting the plurality of drive electrodes; and a scan driving unitperforming a first scan drive and a second scan drive, the first scandrive allowing a display drive signal for driving the display elementsto be applied to each of the plurality of common drive electrodes, thesecond scan drive allowing a touch detection drive signal for detectingan external proximity object to be applied to each of the plurality ofcommon drive electrodes.

A display device according to still another embodiment includes: aplurality of drive electrodes; a plurality of detection electrodesintersecting the plurality of drive electrodes; and a scan driving unitperforming a first scan drive and a second scan drive, the first scandrive allowing a display drive signal to be applied to each of theplurality of common drive electrodes, the second scan drive allowing atouch detection drive signal to be applied to each of the plurality ofcommon drive electrodes at a scan interval different from that of thedisplay drive signal in the first scan drive. When a common driveelectrode selected to be driven in the first scan drive is coincidentwith a common drive electrode selected to be driven in the second scandrive, the scan driving unit applies either the display drive signal orthe touch detection drive signal to the coincident common driveelectrode.

A drive circuit according to an embodiment includes: a scan driving unitperforming a first scan drive and a second scan drive on a display unitwith touch detection, the display unit with the touch detectionincluding display elements, a plurality of common drive electrodesarranged in parallel to extend in one direction, and a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection, the first scan driveallowing a display drive signal for driving the display elements to betime-divisionally applied to each of the plurality of common driveelectrodes in succession, and the second scan drive allowing a touchdetection drive signal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession; and a control unit controlling the scandriving unit. When a common drive electrode selected to be driven in thefirst scan drive is coincident with a common drive electrode selected tobe driven in the second scan drive, the scan driving unit applies eitherthe display drive signal or the touch detection drive signal to thecoincident common drive electrode, and when a common drive electrodeselected to be driven in the first scan drive is different from a commondrive electrode selected to be driven in the second scan drive, the scandriving unit drives the respective common drive electrodes so thatwaveform of the touch detection drive signal transits at a timing withina period accompanied by no waveform transition of the display drivesignal.

A driving method according to an embodiment includes the steps of:performing a first scan drive on the display unit with touch detection;and performing a second scan drive on the display unit with the touchdetection, the display unit with the touch detection including displayelements, a plurality of common drive electrodes arranged in parallel toextend in one direction, and a plurality of detection electrodesarranged in parallel to extend in a direction which intersects thecommon drive electrodes and allowing electrostatic capacitance to beformed at each intersection, the first scan drive allowing a displaydrive signal for driving the display elements to be time-divisionallyapplied to each of the plurality of common drive electrodes insuccession, and the second scan drive allowing a touch detection drivesignal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession. When a common drive electrode selected to bedriven in the first scan drive is coincident with a common driveelectrode selected to be driven in the second scan drive, either thedisplay drive signal or the touch detection drive signal is applied tothe coincident common drive electrode, and when a common drive electrodeselected to be driven in the first scan drive is different from a commondrive electrode selected to be driven in the second scan drive, therespective common drive electrodes are driven so that waveform of thetouch detection drive signal transits at a timing within a periodaccompanied by no waveform transition of the display drive signal.

An electronic unit according to an embodiment includes: a display devicewith touch detection; and a control unit performing an operation controlthat utilizes the display device with the touch detection. The displaydevice with the touch detection including: display elements; a pluralityof common drive electrodes arranged in parallel to extend in onedirection; a plurality of detection electrodes arranged in parallel toextend in a direction which intersects the common drive electrodes andallowing electrostatic capacitance to be formed at each intersection; ascan driving unit performing a first scan drive and a second scan drive,the first scan drive allowing a display drive signal for driving thedisplay elements to be time-divisionally applied to each of theplurality of common drive electrodes in succession, the second scandrive allowing a touch detection drive signal for detecting an externalproximity object to be time-divisionally applied to each of theplurality of common drive electrodes in succession; and a detectioncircuit detecting the external proximity object based on a touchdetection signal which is outputted from the detection electrode inresponse to application of the touch detection drive signal. When acommon drive electrode selected to be driven in the first scan drive iscoincident with a common drive electrode selected to be driven in thesecond scan drive, the scan driving unit applies either the displaydrive signal or the touch detection drive signal to the coincidentcommon drive electrode, and when a common drive electrode selected to bedriven in the first scan drive is different from a common driveelectrode selected to be driven in the second scan drive, the scandriving unit drives the respective common drive electrodes so thatwaveform of the touch detection drive signal transits at a timing withina period accompanied by no waveform transition of the display drivesignal.

The electronic unit is any display device having a function of detectinga touch or proximity, such as a television apparatus, a digital camera,a personal computer, a video camera, and a portable terminal device suchas a cellular phone.

In the display devices with the touch detection according to the firstand second embodiments, and the drive circuit, the driving method, andthe electronic unit according to the embodiments, the display drivesignal and the touch detection drive signal applied to the common driveelectrodes are transmitted to the detection electrodes via theelectrostatic capacitance, and are output as touch detection signals.When the common drive electrode selected to be driven in the first scandrive is different from the common drive electrode selected to be drivenin the second scan drive, the the respective common drive electrodes aredriven so that waveform of the touch detection drive signal transits atthe timing within the period accompanied by no waveform transition ofthe display drive signal. Thereby, the touch detection signalcorresponding to the touch detection drive signal is output separately,from the viewpoint of time, from a signal component corresponding to thedisplay drive signal.

In the display device with the touch detection according to the thirdembodiment, the drive signal applied to the common drive electrodes istransmitted to the detection electrodes via the electrostaticcapacitance, and is output as touch detection signals. The drive signalhas a pulse waveform only in the touch detection period and has a DCwaveform in the display period. Therefore, only the pulse waveform partis transmitted to the detection electrode. Thus, the touch detectionsignal corresponding to the pulse waveform part in the drive signal isoutput from the detection electrode.

In the display device with the touch detection according to the fourthembodiment, the touch detection drive signal applied to the common driveelectrode in the touch detecting unit is transmitted to the detectionelectrode via the electrostatic capacitance and is output as a touchdetection signal. The waveform of the touch detection drive signal isallowed to transit at the timing within the period accompanied by nowaveform transition of the common signal of the display unit. Thereby,for example, even when the common signal is transmitted to the detectionelectrode via the electrostatic capacitance existing between the commonelectrode of the display unit and the detection electrode of the touchdetecting unit, the touch detection signal corresponding to the touchdetection drive signal is outputted separately, from the viewpoint oftime, from a signal component corresponding to the common signal.

Advantageously, the display device with touch detection further includesa pixel signal driving unit supplying a pixel signal to each of thedisplay elements in a display period, and the common drive electrode isdriven so that the waveform of the touch detection drive signal transitsat a timing out of the display period.

Advantageously, the display drive signal has a rectangular waveform witha polarity inverted for every scan line.

Advantageously, the touch detection drive signal is a signal establishedby shifting a phase of the display drive signal.

Advantageously, the detection circuit performs sampling on the touchdetection signal at a preceding timing and a subsequent timing of thewaveform transition timing of the touch detection drive signal, anddetermines the difference between two sampled values.

Advantageously, the plurality of common drive electrodes are partitionedinto blocks each including a predetermined number of common driveelectrodes, and the scan driving unit drives the plurality of commondrive electrodes for each of the blocks.

Advantageously, in the display device with the touch detection accordingto the third embodiment, the pulse waveform includes a section ofpositive voltage and a section of negative voltage with respect to thevoltage of the DC waveform.

Advantageously, in the display device with the touch detection accordingto the third embodiment, a time-averaged voltage of the pulse waveformis equal to the voltage of the DC waveform.

Advantageously, in the display device with the touch detection accordingto the third embodiment, the pulse waveform includes one of a section ofpositive voltage and a section of negative voltage with respect to thevoltage of the DC waveform.

In the display devices with the touch detection according to the firstand the second embodiments, and the drive circuit, the driving method,and the electronic unit according to the embodiments, when the commondrive electrode selected to be driven in the first scan drive isdifferent from the common drive electrode selected to be driven in thesecond scan drive, the respective common drive electrodes are driven sothat waveform of the touch detection drive signal transits at the timingwithin the period accompanied by no waveform transition of the displaydrive signal. Therefore, it is possible to minimize the influence on thedisplay operation of the touch detecting operation.

In the display device with the touch detection according to the thirdembodiment, the drive signal having the DC waveform in the displayperiod and having the pulse waveform in the touch detecting period isapplied to the common drive electrode. Therefore, it is possible tominimize the influence on the display operation by the touch detectingoperation.

In the display device with the touch detection according to the fourthembodiment, the waveform of the touch detection drive signal is allowedto transit at the timing within the period accompanied by no waveformtransition of the common signal. Therefore, it is possible to minimizethe influence on the display operation of the touch detecting operation.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a diagram for explaining the basic principle of a touchdetection method in a display device with a touch detecting functionaccording to embodiments of the present application and showing a statewhere a finger is not yet in contact or in proximity.

FIG. 2 is a diagram for explaining the basic principle of the touchdetection method in the display device with the touch detecting functionaccording to the embodiments of the application and showing a statewhere a finger is in contact or in proximity.

FIG. 3 is a diagram for explaining the basic principle of the touchdetection method in the display device with the touch detecting functionaccording to the embodiments of the application and showing an exampleof the waveforms of a drive signal and a touch detection signal.

FIG. 4 is a block diagram illustrating an example of the configurationof the display device with the touch detecting function according to afirst embodiment.

FIG. 5 is a cross section illustrating a schematic sectional structureof a display unit with a touch detecting function according to the firstembodiment.

FIG. 6 is a circuit diagram illustrating a pixel array of the displayunit with the touch detecting function according to the firstembodiment.

FIG. 7 is a perspective view illustrating an example of theconfiguration of drive electrodes and touch detection electrodes in thedisplay unit with the touch detecting function according to the firstembodiment.

FIG. 8 is a schematic diagram illustrating an example of the operationof a drive electrode driver according to the first embodiment.

FIG. 9 is another diagram illustrating an example of the operation ofthe drive electrode driver according to the first embodiment.

FIG. 10 is an explanatory diagram illustrating the relation of timingsof a display drive signal and a touch detection drive signal accordingto the first embodiment.

FIG. 11 is a timing waveform chart showing an operation example of thedisplay device with the touch detecting function according to the firstembodiment.

FIG. 12 is a waveform chart illustrating an example of the waveform ofthe touch detection signal according to the first embodiment.

FIG. 13 is a timing waveform chart illustrating another operationexample of the display device with the touch detecting functionaccording to the first embodiment.

FIG. 14 is a waveform chart illustrating another waveform example of thetouch detection signal according to the first embodiment.

FIG. 15 is an explanatory diagram illustrating the relation of timingsof a display drive signal and a touch detection drive signal in acomparative example.

FIG. 16 is a timing waveform chart illustrating an operation example ofa display device with a touch detecting function according to thecomparative example.

FIG. 17 is an explanatory diagram illustrating the relation of timingsof a display drive signal and a touch detection drive signal accordingto another modification of the first embodiment.

FIG. 18 is a timing waveform chart illustrating an operation example ofa display device with the touch detecting function according to anothermodification of the first embodiment.

FIG. 19 is a schematic diagram illustrating an example of the operationof a drive electrode driver according to another modification of thefirst embodiment.

FIG. 20 is a schematic diagram illustrating an example of the operationof the drive electrode driver according to another modification of thefirst embodiment.

FIG. 21 is an explanatory diagram illustrating an example of theoperation of a drive electrode driver according to a second embodiment.

FIG. 22 is a timing waveform chart illustrating an operation example ofa display device with a touch detecting function according to the secondembodiment.

FIG. 23 is a waveform chart illustrating an operation example of thedisplay device with the touch detecting function according to the secondembodiment.

FIG. 24 is a timing waveform chart illustrating an operation example ofthe display device with the touch detecting function according to amodification of the second embodiment.

FIG. 25 is a waveform chart illustrating an operation example of thedisplay device with the touch detecting function according to themodification of the second embodiment.

FIG. 26 is a timing waveform chart illustrating an operation example ofthe display device with the touch detecting function according toanother modification of the second embodiment.

FIG. 27 is a perspective view illustrating an appearance configurationof application example 1 of a liquid crystal display device to which theembodiment is applied.

FIGS. 28A and 28B are perspective views illustrating an appearanceconfiguration of application example 2.

FIG. 29 is a perspective view illustrating an appearance configurationof application example 3.

FIG. 30 is a perspective view illustrating an appearance configurationof application example 4.

FIG. 31A is a front view in an open state, FIG. 31B is a side view inthe open state, FIG. 31C is a front view in a closed state, FIG. 31D isa left side view, FIG. 31E is a right side view, FIG. 31F is a top view,and FIG. 31G is a bottom view, each illustrating an appearanceconfiguration of application example 5.

FIG. 32 is a cross section illustrating a schematic sectional structureof a display unit with a touch detecting function according to amodification of each of the embodiments of the application.

FIGS. 33A and 33B are diagrams illustrating an example of the operationof a drive electrode driver according to a modification of each of theembodiments of the application.

DETAILED DESCRIPTION

Embodiments of the present application will be described below in detailwith reference to the drawings.

1. Basic principle of capacitive touch detection

2. First embodiment

3. Second embodiment

4. Application examples

(Basic Principle of Capacitive Touch Detection)

First, with reference to FIGS. 1 to 3, the basic principle of touchdetection in a display device with a touch detecting function (a displaydevice with touch detection) according to embodiments of the presentapplication will be described. The touch detecting method is embodied asa capacitive touch sensor. For example, as illustrated in (A) of FIG. 1,a capacitive element is constructed by using a pair of electrodes (adrive electrode E1 and a touch detection electrode E2) disposed so as toface each other while sandwiching a dielectric D. The structure isexpressed as an equivalent circuit illustrated in (B) of FIG. 1. Acapacitive element C1 is constructed by the drive electrode E1, thetouch detection electrode E2, and the dielectric D. One end of thecapacitive element C1 is connected to an AC signal source (drive signalsource) S, and the other end P is grounded via a resistor R and isconnected to a voltage detector (touch detection circuit) DET. When anAC rectangular wave Sg ((B) of FIG. 3) of a predetermined frequency (forexample, about a few kHz to tens kHz) is applied from the AC signalsource S to the drive electrode E1 (one end of the capacitive elementC1), an output waveform (touch detection signal Vdet) as shown in (A) ofFIG. 3 appears in the touch detection electrode E2 (the other end P ofthe capacitive element C1). The AC rectangular wave Sg corresponds to adrive signal Vcom which will be described later.

In a state where a finger is not in contact (or not in proximity), asillustrated in (A) and (B) of FIG. 1, current I0 according to thecapacitance value of the capacitive element C1 flows in association withcharging/discharging of the capacitive element C1. The potentialwaveform at the other end P of the capacitive element C1 is, forexample, waveform V0 of (A) of FIG. 3 which is detected by the voltagedetector DET.

On the other hand, in a state where a finger is in contact (or inproximity), as illustrated in FIG. 2, a capacitive element C2 formed bythe finger is added in series to the capacitive element C1. In thisstate, currents I1 and I2 flow in association with charging/dischargingof the capacitive elements C1 and C2. The potential waveform at theother end P of the capacitive element C1 at this time is, for example,waveform V1 as illustrated in (A) of FIG. 3, which is detected by thevoltage detector DET. The potential at the point P at this time is avoltage-division potential determined by the values of the currents I1and I2 flowing in the capacitive elements C1 and C2. Consequently, thewaveform V1 has a value smaller than the waveform V0 in a non-contactstate. The voltage detector DET compares the detected voltage with apredetermined threshold voltage Vth and, when the detected voltage isequal to or higher than the threshold voltage, determines that thefinger is in the non-contact state. On the other hand, when the detectedvoltage is less than the threshold voltage, the voltage detector DETdetermines that the finger is in the contact state. In such a manner,touch detection is performed.

2. First Embodiment Configuration Example General Configuration Example

FIG. 4 illustrates a configuration example of a display device with atouch detecting function (a display device with touch detection)according to a first embodiment. A drive circuit and a driving methodfor the display device with the touch detecting function according toembodiments of the application are embodies by this embodiment, so thatthey will be also described. The display device with the touch detectingfunction uses a liquid crystal display element as a display element, andis a device of a so-called in-cell-type obtained by integrating a liquidcrystal display unit constructed by the liquid crystal display elementand a capacitive touch detection unit.

A display device 1 with the touch detecting function includes acontroller 11, a gate driver 12, a source driver 13, a drive electrodedriver 14, a display unit 10 with a touch detecting function, and atouch detection circuit 40.

The controller 11 is a circuit for supplying control signals to the gatedriver 12, the source driver 13, the drive electrode driver 14, and thetouch detection circuit 40 on the basis of a video signal Vdisp suppliedfrom the outside to control so that they operate synchronously with oneanother.

The gate driver 12 has a function of sequentially selecting onehorizontal line to be subjected to the display driving of the displayunit 10 with the touch detecting function on the basis of the controlsignal supplied from the controller 11. Concretely, as will be describedlater, the gate driver 12 applies a scan signal Vscan to the gate of aTFT element Tr of a pixel Pix via a scan signal line GCL to sequentiallyselect, as an object of the display driving, one row (one horizontalline) of pixels Pix formed in a matrix in a liquid crystal display unit20 of the display unit 10 with the touch detecting function.

The source driver 13 is a circuit that supplies the pixel signal Vpix toeach of pixels Pix (which will be described later) in the display unit10 with the touch detecting function on the basis of the control signalsupplied from the controller 11. Concretely, as will be described later,the source driver 13 applies a pixel signal Vpix to each of the pixelsPix constructing one horizontal line sequentially selected by the gatedriver 12 via the pixel signal line SGL. In the pixels Pix, display ofone horizontal line is performed according to the pixel signal Vpixsupplied.

The drive electrode driver 14 is a circuit that supplies the drivesignal Vcom to a drive electrode COML (which will be described later) ofthe display unit 10 with the touch detecting function on the basis ofthe control signal supplied from the controller 11. Concretely, thedrive electrode driver 14 drives the drive electrodes COML on the unitbasis of a block made of predetermined number of drive electrodes COML,supplies a display drive signal Vcomd to a drive electrode block Bperforming display operation and a touch detection drive signal Vcomt toa drive electrode block B performing touch detecting operation. In thetouch detecting operation, by sequentially applying the touch detectiondrive signal Vcomt to a plurality of drive electrode blocks B in atime-divisional manner, a block on which the touch detecting operationis to be performed (detection block) is selected sequentially. A touchdetection unit 30 outputs the touch detection signal Vdet by detectionblocks from a plurality of touch detection electrodes TDL (which will bedescribed later) and supplies the same to the touch detection circuit40.

The display unit 10 with the touch detecting function is a displaydevice having the touch detecting function. The display unit 10 with thetouch detecting function has the liquid crystal display unit 20 and thetouch detection unit 30. As will be described later, the liquid crystaldisplay unit 20 is a device performing display by sequentiallyperforming a scan horizontal-line-by-horizontal-line in accordance withthe gate signal supplied from the gate driver 12. The touch detectionunit 30 operates on the basis of the basic principle of theabove-described capacitive touch detection and outputs the touchdetection signal Vdet. As will be described later, the touch detectionunit 30 performs touch detection by sequentially scanningdetection-block-by-detection-block in accordance with the driveelectrode driver 14.

The touch detection circuit 40 is a circuit for detecting whether thetouch detection unit 30 is touched or not on the basis of the controlsignal supplied from the controller 11 and the touch detection signalVdet supplied from the touch detection unit 30 of the display unit 10with the touch detecting function. In the case where a touch isdetected, the touch detection circuit 40 obtains the coordinates or thelike of the touch in a touch detection region. The touch detectioncircuit 40 has an analog LPF (Low Pass Filter) 42, an A/D converter 43,a signal processor 44, a coordinate extractor 45, and a detection timingcontroller 46. The analog LPF 42 has the coordinate extracting unit 45and the detection timing controller 46. The analog LPF 42 is a low-passanalog filter for removing high frequency components (noise components)included in the touch detection signal Vdet supplied from a touchdetection unit 30, extracting a touch component, and outputting thetouch component. A resistor R for applying DC potential (0V) isconnected between each of the input terminals of the analog LPF 42 andthe ground. In place of the resistor R, for example, a switch may beprovided to apply the DC potential (0V) by being set to the on state inpredetermined time. The A/D converter 43 is a circuit for converting ananalog signal output from the analog LPF 42 to a digital signal. Thesignal processor 44 is a logic circuit for detecting thepresence/absence of a touch in the touch detecting device 30 on thebasis of an output signal of the A/D converter 43. The coordinateextractor 45 is a logic circuit for obtaining touch panel coordinateswhen the touch is detected in the signal processor 44. The detectiontiming controller 46 controls so that those circuits operatesynchronously.

(Display Unit 10 with Touch Detecting Function)

Next, the configuration example of the display unit 10 with the touchdetecting function will be described in detail.

FIG. 5 illustrates an example of a sectional structure of a main part inthe display unit 10 with the touch detecting function. The display unit10 with the touch detecting function has a pixel substrate 2, an opposedsubstrate 3 disposed so as to be opposed to the pixel substrate 2, and aliquid crystal layer 6 disposed between the pixel substrate 2 and theopposed substrate 3.

The pixel substrate 2 has a TFT substrate 21 as a circuit substrate anda plurality of pixel electrodes 22 disposed in a matrix on the TFTsubstrate 21. On the TFT substrate 21, although not illustrated, wiressuch as thin film transistors (TFTs) of pixels, a pixel signal line SGLfor supplying the image signal Vpix to each of the pixel electrodes 22,and a scan signal line GCL for driving each of TFTs are formed.

The opposed substrate 3 has a glass substrate 31, a color filter 32formed on one of the faces of the glass substrate 31, and a plurality ofdrive electrodes COML formed on the color filter 32. The color filter 32is constructed by periodically disposing color filter layers of, forexample, three colors of red (R), green (G), and blue (B), and a set ofthree colors of R, G, and B is associated to each display pixel. Thedrive electrode COML functions as a common drive electrode of the liquidcrystal display unit 20 and also functions as a drive electrode of thetouch detection unit 30. The drive electrode COML is coupled to the TFTsubstrate 21 by a not-shown contact conductive pillar. Via the contactconductive pillar, the drive signal Vcom having the AC rectangularwaveform (the display drive signal Vcomd and the touch detection drivesignal Vcomt) is applied from the TFT substrate 21 to the driveelectrode COML. Although the drive electrode COML corresponds to twopixel electrodes 22 in the diagram, the application is not limitedthereto. For example, the drive electrode COML may correspond to onepixel electrode 22 or three or more pixel electrodes 22. On the otherface of the glass substrate 31, a touch detection electrode TDL as adetection electrode of the touch detection unit 30 is formed. On thetouch detection electrode TDL, a polarizer 35 is disposed.

The liquid crystal layer 6 modulates light passing therethrough inaccordance with the state of the electric field, and uses liquid crystalin various modes such as TN (twisted nematic), VA (vertical alignment),and ECB (electric-field control birefringence) modes.

An alignment film is disposed between the liquid crystal layer 6 and thepixel substrate 2 and between the liquid crystal layer 6 and the opposedsubstrate 3, and an incidence-side polarizer is disposed on the underface side of the pixel substrate 2 (the films are not shown).

FIG. 6 illustrates a configuration example of a pixel structure in theliquid crystal display unit 20. The liquid crystal display unit 20 has aplurality of pixels Pix arranged in a matrix. The pixel Pix has a TFTelement Tr and a liquid crystal element LC. The TFT element Tr isconstructed by a thin film transistor. In the example, the TFT elementTr is constructed by a TFT of an n-channel MOS (Metal OxideSemiconductor) type. The source of the TFT element Tr is connected tothe pixel signal line SGL, the gate is connected to the scan signal lineGCL, and the drain is connected to one end of the liquid crystal elementLC. One end of the liquid crystal element LC is connected to the drainof the TFT element Tr, and the other end is connected to the driveelectrode COML.

The pixel Pix is connected to another pixel Pix belonging to the samerow in the liquid crystal display unit 20 by the scan signal line GCL.The scan signal line GCL is connected to the gate driver 12, and fromthe gate driver 12, the scan signal Vscan is supplied. The pixel Pix isconnected to another pixel Pix belonging to the same column in theliquid crystal display unit 20 by the pixel signal line SGL. The pixelsignal line SGL is connected to the source driver 13, and from thesource driver 13, the pixel signal Vpix is supplied.

Further, the pixel Pix is connected to another pixel Pix belonging tothe same row in the liquid crystal display unit 20 by the driveelectrode COML. The drive electrode COML is connected to the driveelectrode driver 14, and from the drive electrode driver 14, the drivesignal Vcom (the display drive signal Vcomd or the touch detection drivesignal Vcomt) is supplied. In the example, the plurality of pixels Pixbelonging to the same row share the single drive electrode COML. Asshown in FIG. 5, the plurality of pixels Pix belonging to a plurality ofrows (two rows in FIG. 5) may share one drive electrode COML.

With the configuration, in the liquid crystal display unit 20, the gatedriver 12 drives so as to line-sequentially scan the scan signal linensGCL in a time-divisional manner, thereby sequentially selecting onehorizontal line. The source driver 13 supplies the pixel signal Vpix tothe pixels Pix belonging to that one horizontal line, thereby performingdisplay by horizontal-line by horizontal-line. At the time of performingthe display operation, the drive electrode driver 14 applies the displaydrive signal Vcomd to the drive electrode block B including the driveelectrode COML corresponding to that one horizontal line.

FIG. 7 perspectively illustrates a configuration example of the touchdetection unit 30. The touch detection unit 30 is constructed by thedrive electrode COML and the touch detection electrode TDL provided forthe opposed substrate 3. The drive electrode COML is constructed by astripe-shaped electrode pattern extending in the horizontal directionsin the diagram. At the time of performing the touch detecting operation,in each of the electrode patterns, the touch detection drive signalVcomt is sequentially supplied by the drive electrode driver 14 to eachof the drive signal blocks B and, as will be described later, the linesequential scan driving is performed. The touch detection electrode TDLis constructed by a stripe-shaped electrode pattern extending in adirection orthogonal to the extension direction of the electrode patternof the drive electrode COML. The electrode patterns of the touchdetection electrode TDL are connected to the inputs of the analog LPF 42in the touch detection circuit 40. Electrostatic capacitance is formedin the intersecting part of the electrode patterns crossing each otherby the drive electrode COML and the touch detection electrode TDL.

With the configuration, in the touch detection unit 30, at the time ofperforming the touch detecting operation, the drive electrode driver 14drives so as to line-sequentially scan the drive electrode block B in atime-divisional manner, thereby sequentially selecting one detectionblock. By outputting the touch detection signal Vdet from the touchdetection electrode TDL, the touch detection of one detection block isperformed. That is, the drive electrode block B corresponds to the driveelectrode E1 in the basic principle of touch detection illustrated inFIGS. 1 to 3. The touch detection electrode TDL corresponds to the touchdetection electrode E2, and the touch detection unit 30 detects a touchin accordance with the basic principle. As illustrated in FIG. 7, by theintersecting electrode patterns, the capacitive touch sensor isconstructed in a matrix shape. Therefore, by scanning the entire touchdetection face of the touch detection unit 30, the position in which anexternal object comes into contact or proximity is detected.

The liquid crystal element LC corresponds to a concrete example of the“display element” in one embodiment. The drive electrode COMLcorresponds to a concrete example of a “common drive electrode” in oneembodiment. The touch detection electrode TDL corresponds to a concreteexample of a “detection electrode” in one embodiment. The driveelectrode driver 14 corresponds to a concrete example of a “scan drivingunit” in one embodiment. The touch detection circuit 40 corresponds to aconcrete example of a “detection circuit” in one embodiment.

(Operation and Action)

The operation and action of the display device 1 with the touchdetecting function of the embodiment will now be described.

(Outline of General Operation)

The controller 11 supplies the control signals to each of the gatedriver 12, the source driver 13, the drive electrode driver 14, and thetouch detection circuit 40 on the basis of the video signal Vdispsupplied from the outside, to control so that they operate synchronouslywith one another. The gate driver 12 supplies the scan signal Vscan tothe liquid crystal display unit 20 on the basis of the control signalsupplied from the controller 11 to sequentially select one horizontalline as an object of display driving. The source driver 13 supplies thepixel signal Vpix to each of pixels Pix constructing one horizontal lineselected by the gate driver 12, on the basis of the control signalsupplied from the controller 11. The drive electrode driver 14 appliesthe display drive signal Vcomd to the drive electrode block B accordingto one horizontal line in the display operation on the basis of thecontrol signal supplied from the controller 11. In the touch detectingoperation, the drive electrode driver 14 sequentially applies the touchdetection drive signal Vcomt to the drive electrode block B according tothe touch detecting operation, thereby sequentially selecting onedetection block. The display unit 10 with the touch detecting functionperforms the displaying operation on the basis of the signals suppliedfrom the gate driver 12, the source driver 13, and the drive electrodedriver 14, performs the touch detecting operation on the basis of thesignal supplied from the drive electrode driver 14, and outputs thetouch detection signal Vdet from the touch detection electrode TDL. Theanalog LPF 42 removes high frequency components in the touch detectionsignal Vdet and outputs the resultant. The A/D converter 43 converts ananalog signal output from the analog LPF 42 to a digital signal. Thesignal processor 44 detects the presence/absence of a touch in the touchdetecting device 30 on the basis of an output signal of the A/Dconverter 43. The coordinate extractor 45 obtains touch panelcoordinates when the touch is detected in the signal processor 44. Thedetection timing controller 46 controls so that the analog LPF 42, theA/D converter 43, the signal processor 44, and the coordinate extractor45 operate synchronously.

The detailed operation of the display device 1 with the touch detectingfunction will be described below.

(Detailed Operation of Drive Electrode Driver 14)

FIG. 8 schematically illustrates an operation example of the driveelectrode driver 14. FIG. 8 shows operation of applying the drive signalVcom (the display drive signal Vcomd and the touch detection drivesignal Vcomt) by the drive electrode driver 14 to drive electrode blocksB1 to B10 in the case where the display touch detection face S isconstructed by the ten drive electrode blocks B1 to B10. A driveelectrode block Bd is a drive electrode block B to which the displaydrive signal Vcomd is applied. A drive electrode block Bt is a driveelectrode block B to which the touch detection drive signal Vcomt isapplied. In the example, for convenience of explanation, the number ofdrive electrode blocks B is ten, although it is not limited thereto.

In periods P1 to P20, the drive electrode driver 14 sequentially selectsthe drive electrode block Bd as an object of display operation, appliesthe display drive signal Vcomd, and scans all of the drive electrodeblocks B. On the other hand, in each of the periods P1 to P10 and theperiods P11 to P20, the drive electrode driver 14 sequentially selectsthe drive electrode block Bt as an object of the touch detectingoperation, applies the touch detection drive signal Vcomt, and scans allof the drive electrode blocks B. That is, the drive electrode driver 14performs a scan with the touch detection drive signal Vcomt in timewhich is the half of the scan time (1F) with the display drive signalVcomd. The operation in each of the periods P1 to P20 will be describedin detail below.

First, in the period P1, the drive electrode driver 14 selects the driveelectrode block B1 as an object of display driving (drive electrodeblock Bd) and applies the display drive signal Vcomd. Accordingly, inthe display unit 10 with the touch detecting function, both of thedisplay operation and the touch detecting operation are performed in theregion of the drive electrode block B1. That is, in the display unit 10with the touch detecting function, as will be described later, the touchdetecting operation is performed on the basis of the display drivesignal Vcomd.

Next, in the period P2, the drive electrode driver 14 successivelyselects the drive electrode block B1 as an object of display driving(drive electrode block Bd), applies the display drive signal Vcomd,selects the drive electrode block B2 as an object of touch detectiondriving (drive electrode block Bt), and applies the touch detectiondrive signal Vcomt. Accordingly, in the display unit 10 with the touchdetecting function, the display operation is performed in the region ofthe drive electrode block B1, and the touch detecting operation isperformed in the region of the drive electrode block B2.

Similarly, in the periods P3 to P10, the drive electrode driver 14sequentially selects the drive electrode block Bd and applies thedisplay drive signal Vcomd, and sequentially selects the drive electrodeblock Bt and applies the touch detection drive signal Vcomt.Accordingly, in regions of different drive electrode blocks B, thedisplay operation and the touch detecting operation are performed,respectively. In the periods P1 to P10, the drive electrode driver 14finishes the scan for the touch detecting operation on all of the driveelectrode blocks B1 to B10 in the periods P1 to P10.

Next, in the period P11, the drive electrode driver 14 selects the driveelectrode block B6 as the object of the display drive (drive electrodeblock Bd) and applies the display drive signal Vcomd thereto, andselects the drive electrode block B1 as the object of the touchdetection drive (drive electrode block Bt) and applies the touchdetection drive signal Vcomt thereto. By the operation, in the displayunit 10 with the touch detecting function, the display operation isperformed in the region of the drive electrode block B6, and the touchdetecting operation is performed in the region of the drive electrodeblock B1. In such a manner, the drive electrode driver 14 starts a scanof the next touch detecting operation from the period P11.

Similarly, in the period P12 to P19, the drive electrode driver 14sequentially selects the drive electrode blocks Bd and applies thedisplay drive signal Vcomd thereto, and sequentially selects the driveelectrode blocks Bt and applies the touch detection drive signal Vcomtthereto. By the operation, the display operation and the touch detectingoperation are performed in the regions of the different drive electrodeblocks B, respectively.

Next, in the period P20, the drive electrode driver 14 selects the driveelectrode block B10 as an object of the display drive (drive electrodeblock Bd) and applies the display drive signal Vcomd thereto. By theoperation, in the display unit 10 with the touch detecting function,both of the display operation and the touch detecting operation areperformed in the region of the drive electrode block B10. That is, inthe display unit 10 with the touch detecting function, like in theperiod P1, the touch detecting operation is performed on the basis ofthe display drive signal Vcomd.

FIG. 9 schematically illustrates moving operation in the display-touchdetection face S of the drive electrode blocks Bd and Bt shown in FIG.8. As illustrated in FIG. 9, during the drive electrode block Bd issequentially selected and scanned once in the display operation, thedrive electrode block Bt is sequentially selected and scanned twice inthe touch detecting operation. That is, in the example, the scanfrequency of the touch detecting operation is twice as high as that ofthe display operation.

FIG. 10 illustrates the relation of relative timings between the displaydrive signal Vcomd and the touch detection drive signal Vcomt. Thelateral axis indicates period P, and the vertical axis indicates thedrive electrode blocks B to which the display drive signal Vcomd and thetouch detection drive signal Vcomt are applied.

In the period P1, the drive electrode driver 14 applies therectangular-shaped display drive signal Vcomd to the drive electrodeblock B1. In the periods P2 to P19, the drive electrode driver 14sequentially selects the drive electrode blocks B, and applies thedisplay drive signal Vcomd and the touch detection drive signal Vcomt todifferent drive electrode blocks B in each period P. The touch detectiondrive signal Vcomt has a waveform similar to that of the display drivesignal Vcomd, and the phase of the touch detection drive signal Vcomt isadvanced more than that of the display drive signal Vcomd. Desirably,the amplitude of the display drive signal Vcomd and that of the touchdetection signal Vcomt are the same for the reason that a circuit, awiring, a power source, and the like are shared, although it is notlimited thereto. For example, in the case where the amplitude of thetouch detection signal Vcomt is larger than that of the display drivesignal Vcomd, the sensitivity of touch detection is improved. In theperiod P20, although not illustrated, the drive electrode driver 14applies the rectangular-shaped display drive signal Vcomd to the driveelectrode block B10 like in the period P1.

(Detailed Operation of Display Device 1 with Touch Detecting Function)

Next, the detailed operation of the display device 1 with a touchdetecting function will be described with reference to some timingwaveform charts.

FIG. 11 illustrates an example of timing waveforms of the display device1 with a touch detecting function, in the periods P2 to P19. (A)illustrates the waveform of the display drive signal Vcomd, (B)illustrates the waveform of the touch detection drive signal Vcomt, (C)illustrates the waveform of the scan signal Vscan, (D) shows thewaveform of the pixel signal Vpix, and (E) shows the waveform of thetouch detection signal Vdet. In the periods P2 to P19, the display drivesignal Vcomd ((A) of FIG. 11) and the touch detection drive signal Vcom((B) of FIG. 11) are applied to the different drive electrode blocks Bas illustrated in FIGS. 8 and 10. For convenience of explanation, (A) to(E) of FIG. 11 illustrate the operations in one period P of the periodsP2 to P19. That is, in the explanation of (A) to (E) of FIG. 11, it isassumed that the drive electrode blocks Bd and Bt do not move.

The display unit 10 with the touch detecting function performs a touchdetecting operation (touch detection period Tt) and a display operation(display period Td) in a time-divisional manner. In the periods P2 toP19, in the touch detecting operation, when the touch detection drivesignal Vcomt changes and the display drive signal Vcomd does not change,the touch detection is performed on the basis of the touch detectionsignal output from the touch detection electrode TDL. In the following,the operation will be described in detail.

First, the drive electrode driver 14 selects the drive electrode blockBd and applies the display drive signal Vcomd to that drive electrodeblock Bd, and the voltage level changes from the low level to the highlevel ((A) in FIG. 11). By the change, a one display horizontal period(1H) starts. The display drive signal Vcomd is transmitted to the touchdetection electrode TDL like the above-described touch detection drivesignal Vcomt, and the touch detection signal Vdet changes ((E) in FIG.11).

Then, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the (n−1)th row included in the driveelectrode block Bd selected by the drive electrode driver 14, and a scansignal Vscan(n−1) changes from the low level to the high level ((C) inFIG. 11).

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((D) in FIG. 11) to performdisplay of the 1 horizontal line. As illustrated in (E) in FIG. 11,there is the possibility that the change in the pixel signal Vpix istransmitted to the touch detection electrode TDL via a parasitecapacitance and the touch detection signal Vdet changes. However, theA/D converter 43 does not perform sampling in the display period Td, sothat the pixel signal Vpix does not exert influence on the touchdetection. After supply of the pixel signal Vpix of the source driver 13is finished, the gate driver 12 changes the level of a scan signalVscan(n−1) of the scan signal line GCL of the (n−1)th row from the highlevel to the low level ((C) in FIG. 11).

Next, the touch detection period Tt starts. The A/D converter 43 A-Dconverts the touch detection signal Vdet at a sampling timing ts1 of thetouch detection period Tt ((E) in FIG. 11).

Then, the drive electrode driver 14 applies the touch detection drivesignal Vcomt to the drive electrode block Bt, and the voltage levelchanges from the high level to the low level ((B) in FIG. 11). The touchdetection drive signal Vcomt is transmitted to the touch detectionelectrode TDL via an electrostatic capacitance, and the touch detectionsignal Vdet changes ((E) in FIG. 11).

Then, the A/D converter 43 A-D converts the touch detection signal Vdetat a sampling timing ts2 ((E) in FIG. 11). In the signal processor 44 ofthe touch detection circuit 40, touch detection is performed on thebasis of the difference between an A/D conversion result at the samplingtiming ts1 and an A/D conversion result at the sampling timing ts2. Insuch a manner, in the display device 1 with the touch detectingfunction, touch detection of one detection block corresponding to thedrive electrode block Bt is performed.

Then, the drive electrode driver 14 applies the display drive signalVcomd to the drive electrode block Bd ((A) in FIG. 11). After that, thegate driver 12 applies the scan signal Vscan to the scan signal line GCLof pixels in the n-th row included in the drive electrode block Bd, anda scan signal Vscan(n) changes from the low level to the high level ((A)in FIG. 11).

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((D) in FIG. 11) to startdisplaying for one horizontal line. Although the display device 1 withthe touch detecting function performs inversion drive in this example,the polarity of the pixel signal Vpix applied by the source driver 13 isinverted from that of the pixel signal Vpix in the immediately preceding1 display horizontal period. After completion of the supply of the pixelsignal Vpix by the source driver 13, the gate driver 12 changes a scansignal Vscan(n) in the scan signal line GCL in the n-th row from thehigh level to the low level.

Then, at the sampling timing ts1 in the touch detection period Tt, theA/D converter 43 A/D converts the touch detection signal Vdet ((E) inFIG. 11). The drive electrode driver 14 applies the touch detectiondrive signal Vcomt to the drive electrode block Bt ((B) in FIG. 11).After the touch detection signal Vdet changes ((E) in FIG. 11), the A/Dconverter 43 A/D converts the touch detection signal Vdet at thesampling timing ts2 ((E) in FIG. 11). In the signal processor 44 in thetouch detection circuit 40, touch detection is performed on the basis ofthe difference between the A/D conversion result at the sampling timingts1 and the A/D conversion result at the sampling timing ts2.

By repeating the above-described operations hereinafter, the displaydevice 1 with the touch detecting function performs the displayoperation by performing the scanning in the drive electrode block Bdselected in each period P of the periods P2 to P19 and performs thetouch detecting operation on one detection block related to the selecteddrive electrode block Bt. The operations are repeated in all of theperiods P2 to P19.

FIG. 12 illustrates the waveforms of the touch detection signal Vdet inthe periods P2 to P19. In FIG. 12, the waveform L1 is the waveform ofthe touch detection signal Vdet in the case where there is no touch. Thewaveform L2 is the waveform of the touch detection signal Vdet in thecase where there is a touch. In the display device 1 with the touchdetecting function, the amplitude of the touch detection signal Vdetvaries depending on the presence or absence of a touch on the basis ofthe basic principle of the above-described capacitive touch detection.That is, the amplitude of the touch detection signal Vdet in the casewhere there is a touch is smaller than that in the case where there isno touch. The touch detection circuit 40 detects the difference of theamplitudes by sampling the touch detection signal Vdet at the samplingtimings ts1 and ts2 in the touch detection period, thereby detecting thetouch.

FIG. 13 illustrates an example of timing waveforms of the display device1 with a touch detecting function, in the periods P1 and P20. (A)illustrates the waveform of the display drive signal Vcomd, (B)illustrates the waveform of the scan signal Vscan, (C) shows thewaveform of the pixel signal Vpix, and (D) shows the waveform of thetouch detection signal Vdet. In the periods P1 and P20, as describedabove, the drive electrode driver 14 does not output the touch detectiondrive signal Vcomt, and the touch detecting operation is performed onthe basis of the display drive signal Vcomd ((A) in FIG. 13). In otherwords, in the periods P1 and P20, the display drive signal Vcomd is alsoused as the touch detection drive signal Vcomt. For convenience ofexplanation, it is assumed that (A) to (D) in FIG. 13 show theoperations in one of the periods P1 and P20. That is, in the explanationof (A) to (D) of FIG. 13, it is assumed that the drive electrode blocksBd and Bt do not move.

The display device 1 with the touch detecting function performs a touchdetecting operation (touch detection period Tt) and a display operation(display period Td) in a time-divisional manner. In the periods P1 andP20, in the touch detecting operation, when the display drive signalVcomd changes, the touch detection is performed on the basis of thetouch detection signal output from the touch detection electrode TDL. Inthe following, the operation will be described in detail.

First, the drive electrode driver 14 selects the drive electrode blockBd and applies the display drive signal Vcomd to that drive electrodeblock Bd, and the voltage level changes from the low level to the highlevel ((A) in FIG. 13). By the change, a one display horizontal period(1H) starts.

Then, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the (n−1)th row included in the driveelectrode block Bd selected by the drive electrode driver 14, and a scansignal Vscan(n−1) changes from the low level to the high level ((B) inFIG. 13).

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((C) in FIG. 13) to startdisplay of the 1 horizontal line. After completion of the supply of thepixel signal Vpix of the source driver 13, the gate driver 12 changesthe level of the scan signal Vscan(n−1) of the scan signal line GCL ofthe (n−1)th row from the high level to the low level ((B) in FIG. 13).

Next, the touch detection period Tt starts. The A/D converter 43 A-Dconverts the touch detection signal Vdet at the sampling timing ts1 ofthe touch detection period Tt ((D) in FIG. 13).

Then, the drive electrode driver 14 applies the display drive signalVcomd to the drive electrode block Bd, and the voltage level changesfrom the high level to the low level ((A) in FIG. 13). The display drivesignal Vcomd is transmitted to the touch detection electrode TDL via anelectrostatic capacitance, and the touch detection signal Vdet changes((D) in FIG. 13).

Then, the A/D converter 43 A-D converts the touch detection signal Vdetat the sampling timing ts2 ((D) in FIG. 13). In the signal processor 44of the touch detection circuit 40, touch detection is performed on thebasis of the difference between an A/D conversion result at the samplingtiming ts1 and an A/D conversion result at the sampling timing ts2. Insuch a manner, in the display device 1 with the touch detectingfunction, touch detection of one detection block corresponding to thedrive electrode block Bd is performed.

Then, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the n-th row included in the driveelectrode block Bd, and the scan signal Vscan(n) changes from the lowlevel to the high level ((B) in FIG. 13).

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((C) in FIG. 13) to startdisplaying for one horizontal line. After completion of the supply ofthe pixel signal Vpix by the source driver 13, the gate driver 12changes the scan signal Vscan(n) in the scan signal line GCL in the n-throw from the high level to the low level ((B) in FIG. 13).

Then, at the sampling timing ts1 in the touch detection period Tt, theA/D converter 43 A/D converts the touch detection signal Vdet ((D) inFIG. 13). The drive electrode driver 14 applies the display drive signalVcomd to the drive electrode block Bd ((A) in FIG. 13), and the touchdetection signal Vdet changes ((D) in FIG. 13). After that, the A/Dconverter 43 A/D converts the touch detection signal Vdet at thesampling timing ts2 ((D) in FIG. 13). In the signal processor 44 in thetouch detection circuit 40, touch detection is performed on the basis ofthe difference between the A/D conversion result at the sampling timingts1 and the A/D conversion result at the sampling timing ts2.

By repeating the above-described operations hereinafter, the displaydevice 1 with the touch detecting function performs the displayoperation by performing the scanning in the drive electrode block Bdselected in each period P of the periods P1 and P20 and performs thetouch detecting operation on one detection block related to the driveelectrode block Bd.

The sampling timings ts1 and ts2 in the periods P1 and P20 illustratedin FIG. 13 differ from the sampling timings ts1 and ts2 in the periodsP2 to P19 illustrated in FIG. 11. That is, in FIG. 13, the samplingtimings ts1 and ts2 are set before and after the change in the displaydrive signal Vcomd, respectively. In FIG. 11, they are set before thedisplay drive signal Vcomd changes. Since the display device 1 with thetouch detecting function always grasps the drive electrode block B(drive electrode block Bd) as an object of the display operation and thedrive electrode block (drive electrode block Bt) as an object of thetouch detecting operation, the sampling timings ts1 and ts2 in theoperations in the periods P1 and P20 and those in the operation in theperiods P2 to P19 are set different from each other, to control thetouch detection circuit 40.

FIG. 14 illustrates the waveforms of the touch detection signal Vdet inthe periods P1 and P20. In FIG. 14, the waveform L3 is the waveform ofthe touch detection signal Vdet in the case where there is no touch. Thewaveform L4 is the waveform of the touch detection signal Vdet in thecase where there is a touch. The touch detection circuit 40 detects atouch by sampling the touch detection signal Vdet at the samplingtimings ts1 and ts2 of the touch detection period Tt, on the basis ofthe basic principle of the above-described capacitive touch detection.

In this manner, the display device 1 with the touch detecting functionperforms the display operation on the entire display face by performingthe operations as described above in the periods P1 to P20, and performsthe touch detecting operation on the entire touch detection face.

Comparative Example

Next, a display device with a touch detecting function according to acomparative example will be described. In the comparative example, thedisplay drive signal Vcomd and the touch detection drive signal Vcomthave the same phase. That is, in the comparative example, the displaydevice with the touch detecting function is constructed by using a driveelectrode driver 14R which outputs the display drive signal Vcomd andthe touch detection signal Vcomt having such a phase relation. The otherconfiguration is similar to that of the first embodiment described above(refer to FIG. 4 and the like).

FIG. 15 illustrates relative timing relations between the display drivesignal Vcomd and the touch detection drive signal Vcomt in the displaydevice with the touch detecting function according to the comparativeexample. In the display device with the touch detecting functionaccording to the comparative example, in a manner similar to the displaydevice 1 with the touch detecting function according to the embodiment(FIG. 10), in the period P1, the drive electrode driver 14R applies thedisplay drive signal Vcomd having a rectangular shape to the driveelectrode block B1. In the periods P2 to P19, the drive electrode driver14R sequentially selects the drive electrode blocks B and applies thedisplay drive signal Vcomd and the touch detection drive signal Vcomt tothe different drive electrode blocks B in the periods P, respectively.At this time, in the display device with the touch detecting functionaccording to the comparative example, different from the display device1 with the touch detecting function according to the embodiment, thetouch detection drive signal Vcomt has the same phase as that of thedisplay drive signal Vcomd. In the period P20, although not shown, likein the period P1, the drive electrode driver 14R applies the displaydrive signal Vcomd having a rectangular shape to the drive electrodeblock B1.

FIG. 16 illustrates an example of timing waveforms of the display devicewith the touch detecting function according to the comparative example,in the periods P2 to P19. (A) illustrates the waveform of the displaydrive signal Vcomd, (B) illustrates the waveform of the touch detectiondrive signal Vcomt, (C) illustrates the waveform of the scan signalVscan, (D) shows the waveform of the pixel signal Vpix, and (E) showsthe waveform of the touch detection signal Vdet.

First, the drive electrode driver 14R selects the drive electrode blockBd and applies the display drive signal Vcomd to that drive electrodeblock Bd, and the voltage level changes from the low level to the highlevel ((A) in FIG. 16). Simultaneously, the drive electrode driver 14Rselects the drive electrode block Bt and applies the touch detectiondrive signal Vcomt to the selected drive electrode block Bt, and thevoltage level changes from the low level to the high level ((B) in FIG.16). By the change, a one display horizontal period (1H) starts.

Then, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the (n−1)th row included in the driveelectrode block Bd, and a scan signal Vscan(n−1) changes from the lowlevel to the high level ((C) in FIG. 16).

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((D) in FIG. 16) to performdisplay of the 1 horizontal line. After supply of the pixel signal Vpixof the source driver 13 is finished, the gate driver 12 changes thelevel of the scan signal Vscan(n−1) of the scan signal line GCL of the(n−1)th row from the high level to the low level ((C) in FIG. 16).

Then, the A/D converter 43 A-D converts the touch detection signal Vdetat the sampling timing is 1 of the touch detection period Tt ((E) inFIG. 16). The drive electrode driver 14 applies the display drive signalVcomd to the drive electrode block Bd ((A) in FIG. 16) and applies thetouch detection drive signal Vcomt to the drive electrode block Bt ((B)in FIG. 16), and the touch detection signal Vdet changes ((E) in FIG.16). After that, the A/D converter 43 A-D converts the touch detectionsignal Vdet at the sampling timing ts2 ((E) in FIG. 16). In the signalprocessor 44 of the touch detection circuit 40, touch detection isperformed on the basis of the difference between an A/D conversionresult at the sampling timing ts1 and an A/D conversion result at thesampling timing ts2.

By repeating the above-described operations hereinafter while performingthe inverting operation, the display device with the touch detectingfunction according to the comparative example performs the displayoperation by performing the scanning in the drive electrode block Bdselected in each period P of the periods P2 to P19 and performs thetouch detecting operation on two detection blocks related to theselected drive electrode blocks Bd and Bt. The operations are performedin each period P of the periods P1 and P20 in a manner similar to theforegoing embodiment (FIG. 13).

In the comparative example, in each period P of the periods P2 to P19,the touch detection drive signal Vcomt and the display drive signalVcomd have the same phase, so that the touch detecting operation isperformed simultaneously on the two detection blocks. That is, in thecomparative example, as illustrated in FIG. 8, the touch detectingoperation is performed simultaneously on the different drive electrodeblocks Bd and Bt which are selected in each period P of the periods P2to P19. At this time, in the period P11, a touch component appears inthe touch detection signal Vdet regardless of a touch which occurs inany of the drive electrode block B1 (the drive electrode block Bt) andthe drive electrode block B6 (the drive electrode block Bd), forexample. This shows that it is difficult to determined as to whether thetouch is occurred in the drive electrode block B1 (the drive electrodeblock Bt) or in the drive electrode block B6 (the drive electrode blockBd). That is, in the display device with the touch detecting functionaccording to the comparative example, there is the possibility thatdetection of the touch position is not accurately detected. In otherwords, in addition to a desired signal component based on the touchdetecting drive (the drive electrode block Bt), a signal component basedon the display drive (the drive electrode block Bd) appears as displaynoise in the touch detection signal Vdet.

On the other hand, in the embodiment, in each period P of the periods P2to P19, the phase of the touch detection drive signal Vcomt is advancedas compared with that of the display drive signal Vcomd. Consequently,the touch detecting operation is performed on one detection blockrelated to the selected drive electrode block Bt. For example, in FIG.8, in the period P11, a touch component appears in the touch detectionsignal Vdet only when a touch occurs in the drive electrode block B1(the drive electrode block Bt). Consequently, in the display device 1with the touch detecting function in the embodiment, the touch positioncan be detected accurately without being influenced by the displaynoise.

(Effect)

In the embodiment as described above, the phase of the touch detectiondrive signal and that of the display drive signal are deviated orstaggered from each other, so that the touch detection signal accordingto the touch detection drive signal is separated, and the influence ofthe display operation of the touch detecting operation is suppressed tothe minimum.

(Modification 1-1)

In the first embodiment described above, in the periods P2 to P19, thephase of the touch detection drive signal Vcomt is made advance morethan that of the display drive signal Vcomd, although it is not limitedthereto. Instead, for example, the phase of the touch detection drivesignal Vcomt may be made retard from that of the display drive signalVcomd. This example will be described in detail below.

FIG. 17 illustrates relative timing relations between the display drivesignal Vcomd and the touch detection drive signal Vcomt in a displaydevice with a touch detecting function according to the modification.Different from the case of the display device 1 with the touch detectingfunction according to the embodiment (FIG. 10), in the periods P2 toP19, the phase of the touch detection drive signal Vcomt is behind thatof the display drive signal Vcomd.

FIG. 18 illustrates an example of timing waveforms of the display devicewith the touch detecting function according to the modification, in theperiods P2 to P19. (A) illustrates the waveform of the display drivesignal Vcomd, (B) illustrates the waveform of the touch detection drivesignal Vcomt, (C) illustrates the waveform of the scan signal Vscan, (D)shows the waveform of the pixel signal Vpix, and (E) shows the waveformof the touch detection signal Vdet.

First, the drive electrode driver 14 selects the drive electrode blockBd and applies the display drive signal Vcomd to that drive electrodeblock Bd, and the voltage level changes from the low level to the highlevel ((A) in FIG. 18). By the change, a one display horizontal period(1H) starts, and the touch detection period Tt starts. The display drivesignal Vcomd is transmitted to the touch detection electrode TDL via anelectrostatic capacitance, and the touch detection signal Vdet changes((E) in FIG. 18).

Then, the A/D converter 43 A-D converts the touch detection signal Vdetat the sampling timing ts1 of the touch detection period Tt ((E) in FIG.18).

Then, the drive electrode driver 14 selects the drive electrode block Btand applies the touch detection drive signal Vcomt to that driveelectrode block Bt, and the voltage level thereof changes from the lowlevel to the high level ((B) in FIG. 18). The touch detection drivesignal Vcomt is transmitted to the touch detection electrode TDL via theelectrostatic capacitance, and the touch detection signal Vdet changes((E) in FIG. 18).

Then, the A/D converter 43 A-D converts the touch detection signal Vdetat the sampling timing ts2 in the touch detection period Tt ((E) in FIG.18). In the signal processor 44 of the touch detection circuit 40, touchdetection is performed on the basis of the difference between an A/Dconversion result at the sampling timing ts1 and an A/D conversionresult at the sampling timing ts2.

Then, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the (n−1)th row included in the driveelectrode block Bd selected by the drive electrode driver 14, and a scansignal Vscan(n−1) changes from the low level to the high level ((C) inFIG. 18).

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((D) in FIG. 18) to performdisplaying for one horizontal line. After completion of the supply ofthe pixel signal Vpix by the source driver 13, the gate driver 12changes the scan signal Vscan(n−1) in the scan signal line GCL in the(n−1)th row from the high level to the low level ((C) in FIG. 18).

By repeating the above-described operations hereinafter while performingthe inverting operation, the display device with the touch detectingfunction according to the modification performs the display operation byperforming the scanning in the drive electrode block Bd in each period Pof the periods P2 to P19 and performs the touch detecting operation onone detection block related to the selected drive electrode block Bt.The operations are repeated in all of the periods P2 to P19.

(Modification 1-2)

In the foregoing embodiment, when the drive electrode block B as anobject of the display operation and the drive electrode block B as anobject of the touch detecting operation become the same (periods P1 and20), the drive electrode driver 14 applies the display drive signalVcomd to that drive electrode driver B, although it is not limitedthereto. Alternatively, the touch detection drive signal Vcomt may beapplied. FIG. 19 schematically illustrates an operation example of thedrive electrode driver 14 according to this modification. In the periodP1, the drive electrode driver 14 selects the drive electrode block B1as the drive electrode block Bt and applies the touch detection drivesignal Vcomt. Similarly, in the period P20, the drive electrode driver14 selects the drive electrode block B10 as the drive electrode blockBt, and applies the touch detection drive signal Vcomt. In this case, itis possible to allow the sampling timing is to be the same between theoperation in the periods P1, P2 and the operation in the periods P2 toP19.

(Modification 1-3)

In the foregoing embodiment, in some times, the drive electrode block Bas an object of the display operation and the drive electrode block B asan object of the touch detecting operation are the same, although it isnot limited thereto. Alternatively, the drive electrode block B as anobject of the display operation and the drive electrode block B as anobject of the touch detecting operation may be always different fromeach other. In this case, a display device with a touch detectingfunction always operates like in the timing waveform chart of FIG. 11according to the embodiment described above. That is, the display devicedoes not operate in the timing waveform chart of FIG. 13, so that theoperation is simpler.

A concrete example thereof includes a method of setting the scanfrequency of the touch detecting operation and the scan frequency of thedisplay operation to be the same. In this case, the drive electrodeblock Bd as an object of the display operation and the drive electrodeblock Bt as an object of the touch detecting operation move whilemaintaining the relative interval therebetween without approaching eachother or separating from each other, so that they operate alwaysdifferently from each other.

Another concrete example includes a method of, for example, when thedrive electrode block B as an object of the display operation and thedrive electrode block B as an object of the touch detecting operationare likely to be the same in the case where the scan frequency of thetouch detecting operation is higher than that of the display operationlike in the embodiment, making a scan of the touch detecting operationperformed ahead of a scan of the display operation. In this case, withrespect to the drive electrode block B which is scanned first (i.e.,performed ahead), the touch detecting operation is not performed. Themodification is applicable to the case where a relatively wide area suchas a finger is touched or the case where precision of detection of atouch position is not so desired. Deterioration in precision of a touchposition is minimized by performing interpolation using touch detectionresults in neighboring drive electrode blocks B and obtaining a touchdetection result related to the drive electrode block B which is scannedfirst (i.e., performed ahead) in the touch detection circuit 40.

In any of the methods, the drive electrode block Bd as an object of thedisplay operation and the drive electrode block Bt as an object of thetouch detecting operation are always different from each other, so thatthe operation is always performed like in the timing waveform chart ofFIG. 11 described in the foregoing embodiment. That is, since anoperation similar to the timing waveform of FIG. 13 is not performed,the operation is simpler.

3. Second Embodiment

A display device 9 with a touch detecting function according to a secondembodiment will be described. In the second embodiment, a touchdetection signal Vcomt having a pulse waveform in the touch detectingperiod and having a DC waveform in the display period is used, andso-called dot inversion driving in which the polarities of pixel signalsVpix in pixels Pix neighboring each other are opposite to each other isperformed. The configuration of the display device 9 with the touchdetecting function is similar to that of the display device 1 with thetouch detecting function according to the first embodiment illustratedin FIG. 4 except that a drive electrode driver is different from that ofthe first embodiment. In the second embodiment, the display device 9with the touch detecting function is constructed by using a driveelectrode driver 16 which outputs the touch detection drive signal Vcomtas described above. The other configuration is similar to that of thefirst embodiment (FIG. 4). The same reference numerals are designated tocomponents which are substantially the same as those of the displaydevice with the touch detecting function according to the firstembodiment and their description will not be repeated.

FIG. 21 illustrates the operation of applying the pulse waveform of thetouch detection drive signal Vcomt to the drive electrode block B. Inthe periods P1 to P20, the drive electrode driver 16 sequentiallyselects the drive electrode blocks B, and applies the pulse waveform ofthe touch detection drive signal Vcomt to the drive electrode blocks B.Although not illustrated, in the example, the voltage of the touchdetection drive signal Vcomt in the display period is 0V.

In this example, the waveform of the touch detection drive signal Vcomtis a pulse waveform made of positive and negative voltages, and its timeaverage value is 0V. Thereby, for example, the time average value of thepotential difference between both ends of a liquid crystal element LCbecomes 0V, so that deterioration in the liquid crystal element LC suchas burning is minimized.

FIG. 22 illustrates an example of the timing waveforms of the displaydevice 9 with the touch detecting function in the periods P1 to P20. (A)illustrates the waveform of the touch detection drive signal Vcomt, (B)illustrates the waveform of the scan signal Vscan, (C) shows thewaveform of the pixel signal Vpix, and (D) shows the waveform of thetouch detection signal Vdet.

First, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the (n−1)th row, and the scan signalVscan(n−1) changes from the low level to the high level ((B) in FIG.22). By the operation, a one display horizontal period (1H) starts.

Then, in the touch detection period Tt, the drive electrode driver 16selects the drive electrode block Bt, and applies the touch detectiondrive signal Vcomt having a pulse shape to that drive electrode block Bt((D) in FIG. 22). The touch detection drive signal Vcomt is transmittedto the touch detection electrode TDL via an electrostatic capacitance,and the touch detection signal Vdet changes ((D) in FIG. 22).

Then, the A/D converter 43 A-D converts the touch detection signal Vdetat the sampling timing is of the touch detection period Tt, therebydetecting a touch ((D) in FIG. 22). In such a manner, in the displaydevice 9 with a touch detecting function, a touch detection in onedetection block corresponding to the drive electrode block Bt isperformed.

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((C) in FIG. 22) to performdisplaying for one horizontal line. After completion of the supply ofthe pixel signal Vpix by the source driver 13, the gate driver 12changes the scan signal Vscan(n−1) in the scan signal line GCL in the(n−1)th row from the high level to the low level ((B) in FIG. 22) andthe 1 display horizontal period is finished.

Then, the gate driver 12 applies the scan signal Vscan to the scansignal line GCL of pixels in the (n−1)th row which is different from thepreviously-described row, and the scan signal Vscan(n) changes from thelow level to the high level ((B) in FIG. 22). By the operation, thesubsequent one display horizontal period starts.

Then, in the touch detection period Tt, the drive electrode driver 16applies the pulse-shaped touch detection drive signal Vcomt to the driveelectrode block Bt ((A) in FIG. 22). The A/D driver 43 A-D converts achange in the touch detection signal Vdet accompanied thereby ((D) inFIG. 22), thereby detecting a touch in one detection block correspondingto that drive electrode block Bt.

Then, in the display period Td, the source driver 13 applies the pixelsignal Vpix to the pixel signal line SGL ((C) in FIG. 22), and performsdisplaying for one horizontal line. In the example, the display device 9with the touch detecting function performs dot inversion driving, sothat the polarity of the pixel signal Vpix applied by the source driver13 is inverted from that in the immediately preceding one displayhorizontal period. After completion of the display period Td, the onedisplay horizontal period is finished.

By repeating the above-described operations hereinafter, the displaydevice 9 with the touch detecting function performs the displayoperation by scanning the entire display face, and performs the touchdetecting operation by scanning the entire touch detection face.

The touch detection signal Vdet in the touch detection period Tt isgenerated according to the touch detection drive signal Vcomt.Specifically, the larger the amplitude of the touch detection drivesignal Vcomt is, the larger the amplitude of the touch detection signalVdet in the touch detection period Tt is. For example, highersensitivity of a touch panel is achieved. Thus, in the case where theamplitude of the touch detection drive signal Vcomt is made large, it isdesirable to pay attention to withstand voltage and leakage of the TFTelement Tr.

FIG. 23 illustrates the voltage waveform of the drain of the TFT elementTr. To the drain of the TFT element Tr, the pixel signal Vpix issupplied in the display operation. Then, the TFT element Tr is turnedoff and enters a floating state, and during one display frame period(1F), the potential of the pixel signal Vpix is maintained. In the drainof the TFT element Tr, as shown in FIG. 23, each time the touchdetection drive signal Vcomt is applied to the drive electrode block Bin the one display frame period, a voltage change thereof is transmittedto the liquid crystal element LC via a parasitic capacitance (not shown)existing in parallel, and the pulse waveform of the amplitude 2×ΔVcorresponding to the pulse waveform of the touch detection drive signalcomt is superimposed on the potential of the pixel signal Vpix. That is,for example, after the pixel signal Vpix1 is supplied, the voltage ofthe drain of the TFT element Tr becomes ±ΔV, and the maximum voltagebecomes Vpix1+ΔV. Therefore, it is desirable that the amplitude of thepulse waveform of the touch detection drive signal Vcomt and the like beset so that the potential of the drain does not exceed the withstandvoltage of the TFT element Tr.

Also, as illustrated in FIG. 23, in one display frame period in which anegative pixel signal Vpix2 is supplied, the voltage of the drain of theTFT element Tr becomes Vpix2±ΔV, and the minimum voltage becomesVpix2−ΔV. At this time, attention is to be paid to not only thewithstand voltage of the TFT element Tr but also leakage. Specifically,when a negative voltage is applied transiently to the drain of then-type TFT element Tr which is in the off state (waveform C1) and whenthe TFT element Tr is turned on, charges are moved (leaked) via the TFTelement Tr to change the potential of the pixel signal Vpix which isheld, and there is the possibility that the quality of an image therebydeteriorates. Therefore, in this case, it is desirable that theamplitude of the pulse waveform of the touch detection drive signalVcomt and the like be set so that the TFT element Tr does not turn on,or that the gate potential of the TFT element Tr which is in the offstate be set low so as not to cause leakage.

As described above, in this embodiment, the pulse waveform of the touchdetection drive signal is applied to the drive electrode only in thetouch detection period which is different from the display period.Consequently, the display operation and the touch detecting operationare performed completely independent of each other, and the influence ofthe display operation on the touch detecting operation is minimized.

In this embodiment, the drive electrode driver outputs the pulsewaveform of the touch detection drive signal only in the touch detectionperiod, so that the amplitude of the touch detection drive signal is setwithout being restricted by the display operation, and the detectionsensitivity is increased.

The other effects are similar to those in the case of the firstembodiment.

(Modification 2-1)

Although the touch detection drive signal Vcomt has a pulse waveformmade by both of positive and negative voltages in the foregoingembodiment, it is not limited thereto. Alternatively, for example, apositive pulse waveform made of positive voltage or a negative pulsewaveform made of negative voltage may be used. An example of the casewhere the touch detection drive signal Vcomt having the positive pulsewaveform will be described in detail below.

FIG. 24 illustrates an example of the timing waveforms of a displaydevice with a touch detecting function according to this modification.(A) illustrates the waveform of the touch detection drive signal Vcomt,(B) illustrates the waveform of the scan signal Vscan, (C) shows thewaveform of the pixel signal Vpix, and (D) shows the waveform of thetouch detection signal Vdet. As illustrated in (A) in FIG. 24, thewaveform of the touch detection drive signal Vcomt is a pulse waveformmade of only positive voltage, unlike the case of the display devicewith the touch detecting function according to the embodiment describedabove. In this case as well, in a manner similar to the foregoingembodiment, the display operation and the touch detecting operation areperformed.

FIG. 25 illustrates the waveform at a drain terminal of the TFT elementTr in the display device with the touch detecting function according tothis modification. As in the case of the display device 9 with the touchdetecting function according to the foregoing embodiment (FIG. 23), thepulse waveform corresponding to the pulse waveform of the touchdetection drive signal Vcomt is superimposed on the potential of thepixel signal Vpix. At that time, in correspondence with the fact thatthe touch detection drive signal Vcomt has the positive pulse waveformmade of positive voltage, the positive pulse waveform is superimposedalso on the drain terminal of the TFT element Tr. That is, for example,in one display frame period in which a negative pixel signal Vpix2 issupplied, the minimum voltage of the drain of the TFT element Tr becomesVpix2. Consequently, the TFT element Tr is not turned on transiently, sothat the potential of the pixel signal Vpix does not change. Thus, anexcellent image quality is maintained.

This modification is a case where the TFT element Tr of the pixel Pix isformed by using a TFT of an n-channel MOS type. In the case of formingthe TFT element Tr by using a TFT of a p-channel MOS type, themodification is applicable by using, for example, the negative pulsewaveform made of negative voltage as the pulse waveform of the touchdetection drive signal Vcomt.

(Modification 2-2)

Although the touch detection period Tt is provided before the displayperiod Td in the foregoing embodiments, it is not limited thereto.Alternatively, for example, the touch detection period Tt may beprovided after the display period Td or may be provided before and afterthe display period Td. FIG. 26 illustrates an example of the timingwaveform in the case where the touch detection period Tt is providedafter the display period Td. In this case as well, in a manner similarto the foregoing embodiment, the display operation and the touchdetecting operation are performed.

4. Application Examples

Referring now to FIGS. 27 to 31G, application examples of the displaydevices with the touch detecting function mentioned in the foregoingembodiments and the modifications will be described below. The displaydevices with the touch detecting function of the embodiments and thelike are applicable to an electronic unit in all of fields such as atelevision apparatus, a digital camera, a notebook-sized personalcomputer, a portable terminal device such as a cellular phone, a videocamera, or the like. In other words, the display device with the touchdetecting function of the embodiments and the like are applicable toelectronic units in all of fields, which displays a video signal inputfrom the outside or a video signal generated on the inside as an imageor a video image.

Application Example 1

FIG. 27 illustrates the appearance of a television apparatus to whichthe display device with the touch detecting function according to anyone of the embodiments and the like is applied. The television apparatushas, for example, a video display screen unit 510 including a frontpanel 511 and a filter glass 512. The video display screen unit 510 isconstructed by the display device with the touch detecting functionaccording to any one of the foregoing embodiments and the like.

Application Example 2

FIGS. 28A and 28B illustrate the appearance of a digital camera to whichthe display device with the touch detecting function according to anyone of the embodiments and the like is applied. The digital camera has,for example, a light emitting unit 521 for flash, a display unit 522, amenu switch 523, and a shutter button 524. The display unit 522 isconstructed by the display device with the touch detecting functionaccording to any one of the embodiments and the like.

Application Example 3

FIG. 29 illustrates the appearance of a notebook-sized personal computerto which the display device according to any one of the embodiments andthe like is applied. The notebook-sized personal computer has, forexample, a body 531, a keyboard 532 for operation of inputtingcharacters and the like, and a display unit 533 for displaying an image.The display unit 533 is constructed by the display device with the touchdetecting function according to any one of the embodiments and the like.

Application Example 4

FIG. 30 illustrates the appearance of a video camera to which thedisplay device with the touch detecting function according to any one ofthe embodiments and the like is applied. The video camera has, forexample, a body 541, a lens 542 for photographing a subject, provided inthe front-side face of the body 541, a shooting start/stop switch 543,and a display unit 544. The display unit 544 is constructed by thedisplay device with the touch detecting function according to any one ofthe embodiments and the like.

Application Example 5

FIGS. 31A to 31G illustrate the appearance of a cellular phone to whichthe display device with the touch detecting function according to anyone of the embodiments and the like is applied. The cellular phone isconstructed by, for example, coupling an upper casing 710 and a lowercasing 720 by a coupling part (hinge) 730, and has a display 740, asub-display 750, a picture light 760, and a camera 770. The display 740or the sub-display 750 is constructed by the display device with thetouch detecting function according to any one of the embodiments and thelike.

Although the present application has been described above by theembodiment, the modifications, and the examples of application toelectronic units, the present application is not limited to theembodiment and the like but may be variously modified.

In the foregoing embodiments, the display unit 10 with the touchdetecting function is formed by integrating the liquid crystal displayunit 20 using a liquid crystal of any of various modes such as TN, VA,and ECB and the touch detection unit 30. Alternatively, a liquid crystaldisplay unit using a liquid crystal in the transverse electric fieldmode such as an FFS (Fringe Field Switching) or IPS (In-Plane Switching)and the touch detection unit may be integrated. For example, in the caseof using the liquid crystal in the transverse electric field mode, adisplay unit 60 with a touch detecting function is constructed asillustrated in FIG. 32. The diagram illustrates an example of asectional structure of a main part of the display unit 60 with the touchdetecting function, and illustrates a state where a liquid crystal layer6B is sandwiched between a pixel substrate 2B and an opposed substrate3B. The names, functions, and the like of the other parts are similar tothose in the case of FIG. 5, and their description will not be repeated.In this example, unlike the case of FIG. 5, the drive electrode COMLwhich is used for both display and touch detection is formed immediatelyabove the TFT substrate 21 and serves as a part of the pixel substrate2B. The pixel electrode 22 is disposed above the drive electrode COMLvia an insulating layer 23. In this case, all of dielectrics including aliquid crystal layer 6B existing between the drive electrode COML andthe touch detection electrode TDL contribute to formation of acapacitance C1.

Also, in the embodiments, the scanning frequency of the touch detectingoperation is set twice as high as that of the display operation,although it is not limited thereto. Alternatively, the scanningfrequency of the touch detecting operation may be set, for example,three times or four times as high as that of the display operation.FIGS. 33A and 33B schematically illustrate the moving operation in thedisplay/touch detection face S of the drive electrode blocks Bd and Bt.FIG. 33A illustrates the case where the scanning frequency of the touchdetecting operation is three times as high as that of the displayoperation. FIG. 33B illustrates the case where the scanning frequency ofthe touch detecting operation is four times as high as that of thedisplay operation. In FIG. 33A, while the drive electrode blocks Bd aresequentially selected and a scan is performed once in the displayoperation, the drive electrode blocks Bt are sequentially selected and ascan is performed three times in the touch detecting operation. That is,in this example, the scanning frequency of the touch detecting operationis three times as high as that of the display operation. In FIG. 33B,while the drive electrode blocks Bd are sequentially selected and a scanis performed once in the display operation, the drive electrode blocksBt are sequentially selected and a scan is performed four times in thetouch detecting operation. That is, in this example, the scanningfrequency of the touch detecting operation is four times as high as thatof the display operation.

Further, in the foregoing embodiments, the display device with a touchdetecting function is of the so-called in-cell-type obtained byintegrating a liquid crystal display unit and a capacitive touchdetection unit. Alternatively, a display device of an assembly typeobtained by assembling a liquid crystal display unit and a capacitivetouch detection unit as separate members may be used. In this case, theliquid crystal display unit performs displaying by, for example,inverting a drive signal (common drive signal) to be applied to thedrive electrode (common electrode). The touch detection unit has, forexample, an electrode configuration as illustrated in FIG. 7. In amanner similar to the embodiment, the touch detection unit sequentiallyapplies the touch detection drive signal Vcomt to the drive electrodeCOML, and detects a touch on the basis of the touch detection signalVdet output from the touch detection electrode TDL in accordance withthe touch detection drive signal Vcomt. In the case where a capacitanceis formed between the common electrode of the liquid crystal displayunit and the touch detection electrode TDL of the capacitive touchdetection unit, in a manner similar to the foregoing embodiment, thecommon drive signal applied to the common electrode of the liquidcrystal display unit may be transmitted to the touch detection electrodeTDL of the touch detection unit via the capacitance. At this time, byallowing the waveform of the touch detection drive signal Vcomt of thetouch detection unit to change at a timing when the waveform of thecommon drive signal of the liquid crystal display unit does not change,in a manner similar to the foregoing embodiment, the touch detectionsignal Vdet according to the touch detection drive signal Vcomt isseparated, and the influence on the displaying operation of the touchdetecting operation is minimized.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope and without diminishing itsintended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

The invention claimed is:
 1. A display device with touch detection,comprising: display elements; a plurality of common drive electrodesarranged in parallel to extend in one direction; a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unitperforming a first scan drive and a second scan drive, the first scandrive allowing a display drive signal for driving the display elementsto be time-divisionally applied to each of the plurality of common driveelectrodes in succession, the second scan drive allowing a touchdetection drive signal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession; and a detection circuit detecting the externalproximity object based on a touch detection signal which is outputtedfrom the detection electrode in response to application of the touchdetection drive signal or the display drive signal, wherein the scandriving unit is configured to, when a common drive electrode selected tobe driven in the first scan drive is coincident with a common driveelectrode selected to be driven in the second scan drive, apply thedisplay drive signal to the coincident common drive electrode and to notapply the touch detection drive signal to the coincident common driveelectrode, and when a common drive electrode selected to be driven inthe first scan drive is different from a common drive electrode selectedto be driven in the second scan drive, drive the respective common driveelectrodes so that waveform of the touch detection drive signal transitsat a timing within a period accompanied by no waveform transition of thedisplay drive signal, and the detection circuit is configured to, when acommon drive electrode selected to be driven in the first scan drive iscoincident with a common drive electrode selected to be driven in thesecond scan drive, detect the external proximity object based on achange of the touch detection signal upon transition of the waveform ofthe display drive signal instead of a transition of the waveform of thetouch detection drive signal, and when a common drive electrode selectedto be driven in the first scan drive is different from a common driveelectrode selected to be driven in the second scan drive, detect theexternal proximity object based on a change of the touch detectionsignal upon transition of the waveform of the touch detection drivesignal.
 2. The display device with touch detection according to claim 1,further comprising a pixel signal driving unit supplying a pixel signalto each of the display elements in a display period, wherein the commondrive electrode is driven so that the waveform of the touch detectiondrive signal transits at a timing out of the display period.
 3. Thedisplay device with touch detection according to claim 2, wherein thedetection circuit performs sampling on the touch detection signal at apreceding timing and a subsequent timing of the waveform transitiontiming of the touch detection drive signal, and determines thedifference between two sampled values.
 4. The display device with touchdetection according to claim 2, wherein the plurality of common driveelectrodes are partitioned into blocks each including a predeterminednumber of common drive electrodes, and the scan driving unit drives theplurality of common drive electrodes for each of the blocks.
 5. Thedisplay device with touch detection according to claim 1, wherein thedisplay drive signal has a rectangular waveform with a polarity invertedfor every scan line.
 6. The display device with touch detectionaccording to claim 5, wherein the touch detection drive signal is asignal established by shifting a phase of the display drive signal.
 7. Adisplay device with touch detection, comprising: display elements; aplurality of common drive electrodes arranged in parallel to extend inone direction; a plurality of detection electrodes arranged in parallelto extend in a direction which intersects the common drive electrodesand allowing electrostatic capacitance to be formed at eachintersection; a scan driving unit performing a first scan drive and asecond scan drive, the first scan drive allowing a display drive signalfor driving the display elements to be time-divisionally applied to eachof the plurality of common drive electrodes in succession, the secondscan drive allowing a touch detection drive signal for detecting anexternal proximity object to be time-divisionally applied to each of theplurality of common drive electrodes in succession; and a detectioncircuit detecting the external proximity object based on a touchdetection signal which is outputted from the detection electrode inresponse to application of the touch detection drive signal, wherein thescan driving unit is configured to, when a common drive electrodeselected to be driven in the first scan drive is coincident with acommon drive electrode selected to be driven in the second scan drive,apply the display drive signal to the coincident common drive electrodeand to not apply the touch detection drive signal to the coincidentcommon drive electrode, wherein the scan driving unit drives the commondrive electrodes so that a common drive electrode selected to be drivenin the first scan drive is not coincident with a common drive electrodeselected to be driven in the second scan drive, the scan driving unitdrives the respective common drive electrodes so that waveform of thetouch detection drive signal transits at a timing within a periodaccompanied by no waveform transition of the display drive signal, andwherein the detection circuit is configured to, when a common driveelectrode selected to be driven in the first scan drive is coincidentwith a common drive electrode selected to be driven in the second scandrive, detect the external proximity object based on a change of thetouch detection signal upon transition of the display drive signalinstead of a transition of the waveform of the waveform of the touchdetection drive signal.
 8. A display device with touch detection,comprising: a display unit displaying an image, and including displayelements, and a common electrode connected to the display elements; anda touch detecting unit detecting an external proximity object, the touchdetecting unit including: a plurality of common drive electrodesarranged in parallel to extend in one direction; a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unitperforming a scan drive of allowing a touch detection drive signal fordetecting the external proximity object to be time-divisionally appliedto each of the plurality of common drive electrodes in succession; and adetection circuit detecting the external proximity object based on atouch detection signal which is outputted from the detection electrodein response to application of the touch detection drive signal or thedisplay drive signal, wherein a unit which is part of the scan drivingunit and which provides the display and touch detection signals to thecommon electrodes, and the scan driving unit drive the common signal andthe touch detection drive signal so that waveform of the touch detectiondrive signal transits at a timing within a period accompanied by nowaveform transition of the common signal, wherein the scan driving unitis configured to, when a common drive electrode selected to be driven inthe first scan drive is coincident with a common drive electrodeselected to be driven in the second scan drive, apply the display drivesignal to the coincident common drive electrode and to not apply thetouch detection drive signal to the coincident common drive electrode,wherein the detection circuit is configured to, when a common driveelectrode selected to be driven in the first scan drive is coincidentwith a common drive electrode selected to be driven in the second scandrive, detect the external proximity object based on a change of thetouch detection signal upon transition of the waveform of the displaydrive signal instead of a transition of the waveform of the touchdetection drive signal, and wherein the detection circuit is configuredto detect the external proximity object based on a change of the touchdetection signal upon transition of the waveform of the touch detectiondrive signal.
 9. A drive circuit comprising: a scan driving unitperforming a first scan drive and a second scan drive on a display unitwith touch detection, the display unit with the touch detectionincluding display elements, a plurality of common drive electrodesarranged in parallel to extend in one direction, and a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection, the first scan driveallowing a display drive signal for driving the display elements to betime-divisionally applied to each of the plurality of common driveelectrodes in succession, and the second scan drive allowing a touchdetection drive signal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession; a control unit controlling the scan drivingunit; and a detection circuit detecting the external proximity objectbased on a touch detection signal which is outputted from the detectionelectrode in response to application of the touch detection drive signalor the display drive signal, wherein the scan driving unit is configuredto, when a common drive electrode selected to be driven in the firstscan drive is coincident with a common drive electrode selected to bedriven in the second scan drive, apply the display drive signal to thecoincident common drive electrode and to not apply the touch detectiondrive signal to the coincident common drive electrode, and, when acommon drive electrode selected to be driven in the first scan drive isdifferent from a common drive electrode selected to be driven in thesecond scan drive, apply the respective common drive electrodes so thatwaveform of the touch detection drive signal transits at a timing withina period accompanied by no waveform transition of the display drivesignal, and the detection circuit is configured to, when a common driveelectrode selected to be driven in the first scan drive is coincidentwith a common drive electrode selected to be driven in the second scandrive, detect the external proximity object based on a change of thetouch detection signal upon transition of the waveform of the displaydrive signal instead of a transition of the waveform of the touchdetection drive signal, and when a common drive electrode selected to bedriven in the first scan drive is different from a common driveelectrode selected to be driven in the second scan drive, detect theexternal proximity object based on a change of the touch detectionsignal upon transition of the waveform of the touch detection drivesignal.
 10. A driving method, comprising: performing a first scan driveon the display unit with touch detection; and performing a second scandrive on the display unit with the touch detection, the display unitwith the touch detection including display elements, a plurality ofcommon drive electrodes arranged in parallel to extend in one direction,and a plurality of detection electrodes arranged in parallel to extendin a direction which intersects the common drive electrodes and allowingelectrostatic capacitance to be formed at each intersection, the firstscan drive allowing a display drive signal for driving the displayelements to be time-divisionally applied to each of the plurality ofcommon drive electrodes in succession, and the second scan driveallowing a touch detection drive signal for detecting an externalproximity object to be time-divisionally applied to each of theplurality of common drive electrodes in succession, wherein when acommon drive electrode selected to be driven in the first scan drive iscoincident with a common drive electrode selected to be driven in thesecond scan drive, the display drive signal is applied to the coincidentcommon drive electrode and the touch detection drive signal is notapplied to the coincident common drive electrode, and the externalproximity object is detected based on a change of a touch detectionsignal upon transition of the waveform the display drive signal insteadof a transition of the waveform the touch detection drive signal,wherein when a common drive electrode selected to be driven in the firstscan drive is different from a common drive electrode selected to bedriven in the second scan drive, the respective common drive electrodesare driven so that waveform of the touch detection drive signal transitsat a timing within a period accompanied by no waveform transition of thedisplay drive signal and the external proximity object is detected basedon a change of the touch detection signal upon transition of thewaveform of the touch detection drive signal.
 11. An electronic unitcomprising: a display device with touch detection; and a control unitperforming an operation control that utilizes the display device withthe touch detection, the display device with the touch detectionincluding: display elements; a plurality of common drive electrodesarranged in parallel to extend in one direction; a plurality ofdetection electrodes arranged in parallel to extend in a direction whichintersects the common drive electrodes and allowing electrostaticcapacitance to be formed at each intersection; a scan driving unitperforming a first scan drive and a second scan drive, the first scandrive allowing a display drive signal for driving the display elementsto be time-divisionally applied to each of the plurality of common driveelectrodes in succession, the second scan drive allowing a touchdetection drive signal for detecting an external proximity object to betime-divisionally applied to each of the plurality of common driveelectrodes in succession; and a detection circuit detecting the externalproximity object based on a touch detection signal which is outputtedfrom the detection electrode in response to application of the touchdetection drive signal or the display drive signal, wherein the scandriving unit is configured to, when a common drive electrode selected tobe driven in the first scan drive is coincident with a common driveelectrode selected to be driven in the second scan drive, apply thedisplay drive signal to the coincident common drive electrode and to notapply the touch detection drive signal to the coincident common driveelectrode, and when a common drive electrode selected to be driven inthe first scan drive is different from a common drive electrode selectedto be driven in the second scan drive, drive the respective common driveelectrodes so that waveform of the touch detection drive signal transitsat a timing within a period accompanied by no waveform transition of thedisplay drive signal, and the detection circuit is configured to, when acommon drive electrode selected to be driven in the first scan drive iscoincident with a common drive electrode selected to be driven in thesecond scan drive, detect the external proximity object based on achange of the touch detection signal upon transition of the waveform ofthe display drive signal instead of a transition of the waveform of thetouch detection drive signal, and when a common drive electrode selectedto be driven in the first scan drive is different from a common driveelectrode selected to be driven in the second scan drive, detect theexternal proximity object based on a change of the touch detectionsignal upon transition of the waveform of the touch detection drivesignal.
 12. A display device comprising: a plurality of driveelectrodes; a plurality of detection electrodes intersecting theplurality of drive electrodes; a scan driving unit performing a firstscan drive and a second scan drive, the first scan drive allowing adisplay drive signal for driving the display elements to be applied toeach of a plurality of common drive electrodes, the second scan driveallowing a touch detection drive signal for detecting an externalproximity object to be applied to each of the plurality of common driveelectrodes; and a detection circuit detecting an external proximityobject based on a touch detection signal which is outputted from thedetection electrode in response to application of the touch detectiondrive signal or the display drive signal, wherein the scan driving unitis configured to, when a common drive electrode selected to be driven inthe first scan drive is coincident with a drive electrode selected to bedriven in the second scan drive, apply the display drive signal to thecoincident common drive electrode and to not apply the touch detectiondrive signal to the coincident common drive electrode, and when a commondrive electrode selected to be driven in the first scan drive isdifferent from a drive electrode selected to be driven in the secondscan drive, drive the respective drive electrodes so that waveform ofthe touch detection drive signal transits at a timing within a periodaccompanied by no waveform transition of the display drive signal, andthe detection circuit is configured to, when a common drive electrodeselected to be driven in the first scan drive is coincident with acommon drive electrode selected to be driven in the second scan drive,detect the external proximity object based on a change of the touchdetection signal upon transition of the waveform of the display drivesignal instead of a transition of the waveform of the touch detectiondrive signal, and when a common drive electrode selected to be driven inthe first scan drive is different from a common drive electrode selectedto be driven in the second scan drive, detect the external proximityobject based on a change of the touch detection signal upon transitionof the waveform of the touch detection drive signal.
 13. A displaydevice comprising: a plurality of drive electrodes; a plurality ofdetection electrodes intersecting the plurality of drive electrodes; ascan driving unit performing a first scan drive and a second scan drive,the first scan drive allowing a display drive signal to be applied toeach of the plurality of common drive electrodes, the second scan driveallowing a touch detection drive signal to be applied to each of theplurality of common drive electrodes at a scan interval different fromthat of the display drive signal in the first scan drive; and adetection circuit detecting an external proximity object based on atouch detection signal which is outputted from the detection electrodein response to application of the touch detection drive signal or thedisplay drive signal, wherein when a common drive electrode selected tobe driven in the first scan drive is coincident with a common driveelectrode selected to be driven in the second scan drive, the scandriving unit applies the display drive signal to the coincident commondrive electrode and does not apply the touch detection drive signal tothe coincident drive electrode, and the detection circuit detects theexternal proximity object based on a change of the touch detectionsignal upon transition of the waveform of the display drive signalinstead of a transition of the waveform of the touch detection drivesignal.